HeavyJet From , joined Dec 1969, posts, RR: Reply 1, posted (12 years 2 months 2 weeks 2 days 20 hours ago) and read 2774 times:
I don't know what the max speed is for the B747-400, but I'm guessing it's around .88/.90 mach.
Thrust requirements to attain and maintain that speed at altitude is less than max contiuous thrust for any of the engine types used on the 747. Also, max speed of a jet is more dependent on wing design.
AJ From Australia, joined Nov 1999, 2380 posts, RR: 26 Reply 2, posted (12 years 2 months 2 weeks 2 days 15 hours ago) and read 2752 times:
For both our RR and GE powered aircraft it is 365kcas or 0.92 mach. These speeds can be further limited by Va at lower altitudes.
I'm not sure about PW powered aircraft, but as these are airframe/control limitations I imagine it will have the same.